Preparation of flavor-enhanced reduced calorie fried foods

ABSTRACT

The flavor of fried foods, such as potato chips, prepared in poly(dimethylsiloxane) fluid (silicone oil) is effectively enhanced when a flavor-enhancing component of animal or vegetable fats or oils is added to the silicone oil. Selected flavor-enhancing components include fatty acids, fatty acid esters, fatty alcohols, and mono- and di-glycerides. The flavor-enhancing component will be soluble in the silicone oil, and preferably will function to enhance flavor and aroma, as well as to reduce undesired foaming which can be associated with frying foods in silicone fluid.

This is a continuation of application Ser. No. 08/150,255, as filed Nov.10, 1993, now abandoned which is a continuation of application Ser. No.07/958,708, filed Oct. 9, 1992, now abandoned.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to the preparation of reducedcalorie fried foods, especially fried snack foods such as potato chips.More particularly, the invention relates to improvements inreduced-calorie fried foods which are prepared by frying in a siliconefluid. The inclusion in the silicone fluid of at least a minor amount ofone or more flavor-enhancing additives that are constituents ofnaturally-occurring animal or vegetable fats or oils has been found toimprove the deep-fat fried flavor and aroma of the fried foods. As anadded benefit, the flavor-enhancing additive also will reduce foamingduring frying.

2. Background Art

The preparation of fried foods in a medium other thannaturally-occurring animal or vegetable fats and oils has long beenviewed as advantageous from the standpoint of reducing the overallcalorie content of the foods. In many fried snack foods, such as potatochips, the residual frying oil content of the finished productcontributes more to the calorie content of the product than any otheringredient. As consumer trends place reduced-calorie or "light" foods inmore and more favor, there remains a need to provide such foods so as tomeet consumer demand.

The use of a frying medium which reduces the overall calorie content offried foods has long been regarded as desirable. Fat contributes avariety of important functions as an ingredient in food products,however. Due to its excellent heat transfer properties, animal andvegetable fats and oils perform well as a cooking medium. While theability to provide reduced-fat (and thus reduced-calorie food) productsis of great commercial interest, the full commercial potential will notbe realized unless the food products have a full complement of sensorycharacteristics (e.g. taste, texture and "mouthfeel") that are as goodas, or nearly as good as, their higher-calorie, animal or vegetablefat-containing commercial counterparts.

The use of silicone fluid for the preparation of calorie-reduced friedfoods has received considerable attention in the literature. PublishedEuropean Patent Application 205,273 A2 (C. L. Frye, Dow Corning Corp.,published Dec. 17, 1986) describes the use of silicone fluids asreplacements for natural fats and oils in a variety of foods. Severalexamples in the publication illustrate the preparation of fried foods insilicone fluid.

Morehouse and Zabik (Evaluation of Polydimethylsiloxane Fluids asNon-Caloric Frying Media, J. Food Science, 54 (4), pp. 1061-65 (1989))have identified 35 cSt (centistoke) polydimethylsiloxane as the mostpreferred frying media of the many viscosity grades ofpolydimethylsiloxane fluid which are available. Potato slices can befried in 35 cSt polydimethylsiloxane with considerable foaming to makepotato chips. These chips have good texture but lack the typical flavorsassociated with chips prepared in vegetable oils. Accordingly, chipsprepared in silicone fluid received lower scores in taste panels thanconventional chips.

U.S. Pat. No. 4,983,413 (Meyer et al., Jan. 8, 1991) also relates to thepreparation of reduced-calorie foods by the incorporation of siliconefluids as replacements for natural fats or oils. Although potato slicescan be fried in a 95:5% blend of dimethylpolysiloxane (350 cSt) andconventional frying oil, as stated in the patent, I have found that a95% blend of polydimethylsiloxane fluid of 35 cSt viscosity andconventional frying oil foams unacceptably in frying. Thus, such amixture of conventional frying oil and polydimethylsiloxane (35 cSt)appears relatively unsuitable for the preparation of fried foods.

Silicone fluid has many advantageous qualities as a prospective fryingmedium, including thermal stability and non-digestibility.Unfortunately, the fluid has an overall bland flavor in comparison tonatural animal and vegetable fats traditionally used for preparing friedfoods. Also, as mentioned earlier, silicone fluids tend to foam whenused as a frying medium. Thus, improvements are needed to silicone fluidfrying if food products prepared therein are to become commerciallyviable.

Accordingly, it is an object of the present invention to provide animproved method for preparing reduced-calorie fried foods. Such a methoddesirably takes advantage of the beneficial properties possessed bysilicone fluid, while providing the desirable flavor notes and aromastraditionally associated with foods fried in naturally-occurring animalor vegetable fats or oils.

SUMMARY OF THE INVENTION

The foregoing and other objects have now been attained by the process ofthe present invention. In one aspect the invention provides a method ofpreparing a food product, comprising frying a food in a frying mediumcomprising poly(dimethylsiloxane) and flavor-enhancing component of aplant or animal fat or oil. The flavor-enhancing component should bepresent in an amount effective to impart to the cooked product a flavorand/or aroma normally associated with product fried in animal orvegetable fat or oil. Preferred flavor-enhancing components areconstituents of (or chemically-modified derivatives of suchconstituents) animal or vegetable fats or oils, other than thetriglyceride components of such fats or oils. Many such components areknown in the trade as food-grade emulsifying agents and typicallycontain a fatty acid radical. While the effective amount of suchflavor-enhancing component can vary from component to component, wellless than 5% by volume (v/v) typically is needed to attain the desiredfried food flavor notes in the food product. Less than 1% by volume andeven less than 0.1% of some flavor-enhancing components (based on thevolume of the silicone fluid) are effective to attain the desiredcharacteristics in the end product.

It is generally understood that naturally-occurring animal and vegetablefats and oils are complex mixtures. It has now been discovered thatalthough the triglyceride component of such fats and oils issubstantially immiscible in poly(dimethylsiloxane), and tends to causeunacceptable foaming during frying if added thereto, other components ofanimal or vegetable (plant) fats and oils, as well as derivativesthereof, are reasonably soluble therein. These "flavor-enhancingcomponents," when dissolved in poly(dimethylsiloxane) fluid, provideenhanced flavor and aroma which is reminiscent of natural oils and fats.Preferred flavor-enhancing components also function as surfactants toactually reduce the tendency of the silicone fluid to foam during thecooking process. Thus, a mixture of poly(dimethylsiloxane) fluid and oneor more flavor-enhancing component(s) of natural fats or oils providesan excellent medium for the preparation of reduced-calorie fried foods.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention, a wide variety of fried foodsare prepared by frying in a medium which comprisespoly(dimethylsiloxane) fluid with a flavor-enhancing component derivedfrom a plant or animal fat or oil dissolved therein. For the purposes ofdefining the "flavor-enhancing component," it is important to note thatsuch term excludes naturally-occurring animal and vegetable fats andoils per se. More particularly, a "flavor-enhancing component" should besubstantially free of both triglycerides and lecithin--two components offats and oils that appear to promote foaming when present in siliconefluid frying medium. Thus, it can be said that a flavor-enhancingcomponent consists essentially of one or more of the componentsenumerated herein, such as fatty acids, fatty acid derivatives,monoglycerides and diglycerides. Triglycerides and lecithin, if presentin trace amount, should be present only to the extent that they do notcontribute to foaming.

The use of poly(dimethylsiloxane) fluid in the preparation of friedfoods is described in detail in Morehouse et al., referenced earlier andincorporated by reference herein. Poly(dimethylsiloxane) fluids withvarious viscosities are commercially available from Dow Corning Corp.,Midland, Mich. Frying is conducted under typical frying conditions, forexample at temperatures in the 180° to 190° C. range.

Poly(dimethylsiloxane) fluid of about 35 cSt viscosity presently ispreferred for use in the present invention. This viscosity fluidprovides frying rates similar to commonly used vegetable oils, such assoybean and cottonseed oils. Higher viscosity silicone fluids have beenfound to require longer frying times and thus are less preferred.

A variety of flavor-enhancing components of natural animal and vegetablefats and oils are suitable for use in accordance with the presentinvention. Those skilled in the art will recognize that, inasmuch asnatural fats and oils are complex mixtures, there is no single componentor set of components that can be unequivocally regarded as responsiblefor providing traditional "fried food" flavor notes and aroma. Rather,those of ordinary skill in this field will readily determine that manycomponents of natural fats and oils are relatively soluble inpoly(dimethylsiloxane) fluid. These soluble components are potentiallysuitable for use in the present invention.

Several flavor-enhancing components were tested for solubility at the 1%by weight level in poly(dimethylsiloxane). Linoleic acid (technicalgrade, Pfaltz and Bauer), soybean fatty acids (Witco Industrene 226 FG)and acylated monoglycerides (Myvacet) were found to be soluble at 25° C.Oleyl alcohol (Aldrich) was partially soluble at 25° C. but completelymiscible at higher temperatures. Similarly, mono- and di-glycerides(DurEm 114K) were soluble at 60° C. and stearic acid (Sigma) was solubleat 180° C.

In general, fatty acids and food grade emulsifying agents containingfatty acid residues, such as monoglycerides and diglycerides, arepreferred flavor-enhancing components for use in the present invention.These components are well known and characterized, and can be employedas an additive either in relatively pure form or as a component of adefined or somewhat undefined preparation. See, for example, the list ofemulsifiers in U.S. Pat. Nos. 5,080,921 and 5,082,864 which areincorporated by reference herein. Also see the list of emulsifiers foundin "Functional Properties of Food Components," Yeshajahu Pomerantz,Academic Press, pp. 340 et seq., 1985, also incorporated by referenceherein. Other flavor-enhancing components, for the purposes of theinvention, include monoglycerides, diglycerides, acylated monoglyceridesand certain fatty acid esters including polyglycerol fatty acid esters.For example, fatty acids may be esterified with propylene glycol orsucrose.

The most preferred additives are the GRAS ("generally recognized assafe") oleic or linoleic acid esters, mono- and di-glycerides and fattyacids having iodine values (a measure of saturation) of >85. Otherpreferred, but regulated additives, include polyol fatty acid esters,polyoxyethylene sorbitan fatty acid esters, acetylated mono- anddi-glycerides, diacetyl tartaric acid esters of monoglycerides andcitrate esters of monoglycerides having iodine values of about 30-85.Less preferred are lecithin and triglycerides, which have not been seento reduce foaming of silicone fluid.

In addition to the naturally-occurring components of animal andvegetable fats and oils, it should thus be apparent thatchemically-modified derivatives thereof are suitable for use in thepresent invention.

Preferred fatty acids include oleic and linoleic acids. (Stearic acidand derivatives thereof are useful to reduce foaming, but generally donot contribute to the fried food flavors which are desired.) The usefulfatty acid derivatives include glycerol monooleate, glycerolmonolinoleate, glycerol monooleate diacetate, glycerol monolinoleatediacetate, glycerol oleate linoleate acetate, oleyl alcohol, linoleylalcohol, and oleic and linoleic esters of polyglycerols. The variousflavor-enhancing components may be used alone or in variouscombinations, and are commercially available from a variety of sources.

Although flavor-enhancing materials are referred to herein as"components" of animal or vegetable fats or oils, the additives need notbe purified from or obtained from such fats or oils.Synthetically-sourced additives as well as additives actually derivedfrom naturally-occurring fats and oils are within the definition of"flavor-enhancing components" of the present invention.

In general, less than about 1.0% by volume (on a v/v basis based on thevolume of silicone fluid) and preferably less than about 0.1% by volumeof flavor-enhancing component is required in the poly(dimethylsiloxane)in order to realize improved fried food flavor notes and aroma in thefinal product. The optimal level of any particular component orcombination of components will be routinely arrived at by those ofordinary skill in this field with due regard to flavor and surfactantproperties. As shown herein, some additives are effective in the rangeof about 10 to 100 parts per million (ppm).

Those skilled in this field will appreciate that a wide variety of foodsare suitable for frying or other preparation in the frying media of thisinvention. For example, potato chips are prepared by frying potatoslices in the media. Other foods which may be prepared in these fryingmedia include popcorn, vegetable pieces, meats, fish portions and frieddough products including doughnuts. Indeed, it appears that any foodswhich are suitable for preparation in animal or vegetable fats aresuitable for preparation in the present media.

The following Examples illustrate the present invention. The Examplesprovide useful illustrations of the invention, but are not intended tolimit the scope of the invention or the patent claims which follow.

EXAMPLES Example 1

Poly(dimethylsiloxane) (700 g, 35 cSt, Dow Corning Corporation) wasweighed into a Presto Fry Baby electric deep fryer and heated to 180° C.Potato slices of uniform size were prepared by slicing potatoes to 0.095inch thickness and cutting into circles with a 60 mm diameter cookiecutter. Slices were washed with water and blotted dry. Six slicesprovided 21-24 g potato for frying. Two batches of six slices each werefried in the hot poly(dimethylsiloxane) with considerable foaming. Themaximum foam height occurred about 1 minute into the fry and thensubsided. The maximum foam height was recorded and averaged for the twobatches. Ten microlitres (0.01 g) soybean fatty acid (Witco Industrene226 FG) were added to the hot oil and two more batches were fried,recording the foam height each time. Frying was repeated withconsecutive fatty acid additions of 0.1 mL (0.09 g), 0.7 mL (0.63 g),and 3.5 mL (3.02 g) into the hot oil. Results are recorded in the tablebelow. Minimum foaming occurred with the addition of 140 ppm soybeanfatty acids. Smoking was observed at the highest additive level (0.5%).

    ______________________________________                                        Effect of Soybean Fatty Acid Additive                                         on Foam Height in PDMS-35                                                     total mg                                                                              conc     foam height                                                                              foam vol.                                         added   (ppm)    (cm)       (cc)    % reduction                               ______________________________________                                        0       0        6.0        1132    0                                         10      14       4.2        793     30                                        100     143      3.7        698     38                                        730     1043     4.3        811     28                                        3750    5357     4.3        811     28                                        ______________________________________                                    

Example 2

Larger quantities of chips for taste panels were prepared in a WellsF-101 Fryer containing 15 kg of 35 cSt polydimethylsiloxane and 15-30g(0.1-0.2%) food grade soya fatty acid (Humko Industrene 226 FG). Thepanel judged the oil flavor to be somewhat stronger and the overallacceptability somewhat lower than commercially-available RUFFLES® brandpotato chips.

Example 3

The following additional flavor-enhancing additives, all commerciallyavailable from the Grinsted Co., were evaluated for use in accordancewith the present invention: Monoglycerides derived from sunflower oil(Dimodan LS, iodine value 110), partially hydrogenated soybean oil(Dimodan 0, iodine value 60), or lard (Dimodan S, iodine value 50);diacetyl tartrate ester of monoglycerides derived from lard (Panodan SD,iodine value of 80); polyglycerol ester (Triodan 20, iodine value of80). Each of the additives are of GRAS status, and imparted good flavorand aroma associated with potato chips prepared in naturally occurringoils.

Foam height was measured in centimeters during the course of frying 19to 21 g of potato slices in accordance with the general procedure ofExample 1. Additive levels of approximately 10, 100, 200, or 1000 ppmwere tested.

Monoglycerides (Dimodan LS, Of or S) were the least effective defoamers.Only 10% foam reduction was found at 100 ppm addition. Foaming waspromoted at 10 and 1000 ppm. Dimodan LS and other more saturatedDimodans (O,S) were ineffective defoamers at 200 ppm.

The diacetyl tartaric esters of monoglycerides, Panodan SD, gave about20% foam reduction throughout the 10-1000 ppm range.

A polyglycerol ester, Triodan 20, gave no foam reduction at 10 ppm, but20% or more reduction at concentrations over 100 ppm.

Although the present invention has been described in connection withcertain preferred embodiments and specific examples, it is not solimited. Modification and variations will become apparent to thoseskilled in this field of food science and chemistry.

I claim:
 1. A method of preparing a fried food product, comprising frying a food in a frying medium free from naturally-occurring animal and vegetable fats and oils and comprising poly(dimethylsiloxane) and a flavor-enhancing additive consisting essentially of a component, or a chemically-modified component, of a plant or animal fat or oil in an amount less than 5% by volume and effective to impart to the fried food product a flavor or aroma normally associated with a product fried in animal or vegetable fat or oil.
 2. A method according to claim 1 wherein the flavor-enhancing component is a fatty acid or a food-grade emulsifying agent containing a fatty acid radical.
 3. A method according to claim 1 wherein the flavor-enhancing component is a monoglyceride.
 4. A method according to claim 1 wherein the flavor-enhancing component is a diglyceride.
 5. A method according to claim 1 wherein the flavor-enhancing component is an acylated monoglyceride.
 6. A method according to claim 1 wherein the flavor-enhancing component is a fatty acid ester.
 7. A method according to claim 1 wherein the flavor-enhancing component consists essentially of one or more members of the group consisting of oleic acid, linoleic acid, glycerol monooleate, glycerol monolinoleate, glycerol monooleate diacetate, glycerol monolinoleate diacetate, glycerol oleate linoleate acetate, oleyl alcohol, linoleyl alcohol, and oleic and linoleic esters of polyglycerols.
 8. A method according to claim 6 wherein the flavor-enhancing component is a fatty acid which is esterified with propylene glycol or sucrose.
 9. A method according to claim 2 wherein the fatty acid is linoleic acid or oleic acid.
 10. A method according to claim 1 wherein the cooking medium comprises less than about 1.0% v/v of the flavor-enhancing component.
 11. A method according to claim 1 wherein the poly(dimethylsiloxane) has a viscosity of about 35 cSt.
 12. A method according to claim 1 wherein the frying medium is comprised of less than about 0.1% v/v of the flavor-enhancing component.
 13. A method for preparing a reduced-calorie food product comprising cooking a food product in a cooking medium free from naturally-occurring animal and vegetable fats and oils and comprising poly(dimethylsiloxane) fluid and an amount of a flavor-enhancing additive effective to impart to the product a flavor associated with frying in a naturally-occurring animal or vegetable fat or oil.
 14. A method according to claim 13 wherein said amount is less than about 1.0% v/v.
 15. A method according to claim 13 wherein said amount is less than about 0.1% v/v.
 16. A method according to claim 13 wherein the flavor enhancing additive is selected from the group consisting of fatty acid, monoglyceride and diglyceride.
 17. A method according to claim 13 wherein the flavor enhancing additive is selected from the group consisting of monoglyceride, diglyceride, acylated monoglyceride and fatty acid ester.
 18. A method for preparing reduced-calorie potato chips comprising cooking potato slices in a cooking medium free from naturally-occurring animal and vegetable fats and oils and comprising poly(dimethylsiloxane) fluid and an amount of a flavor-enhancing additive effective to impart to the potato chips a flavor associated with potato chips prepared in a naturally-occurring animal or vegetable fat or oil.
 19. A method according to claim 18 wherein the flavor-enhancing additive is selected from the group consisting of fatty acid, monoglyceride, diglyceride, acylated monoglyceride and fatty acid ester.
 20. A method according to claim 19 wherein said amount is less than about 1% v/v.
 21. A method according to claim 19 wherein said amount is less than about 0.1% v/v.
 22. In a method for preparing a fried food product by frying a food in poly(dimethylsiloxane) fluid, the improvement comprising frying the food in a mixture free from naturally-occurring animal and vegetable fats and oils comprising poly(dimethylsiloxane) and about 1% v/v or less of a flavor enhancing additive selected from the group consisting of fatty acid, monoglyceride and diglyceride.
 23. An edible food product prepared by frying a food in a frying medium free from naturally-occurring animal and vegetable fats and oils and comprising poly(dimethylsiloxane) fluid and an amount of a flavor enhancing additive effective to impart to the product a flavor associated with frying in a naturally-occurring animal or vegetable fat or oil.
 24. A product according to claim 23 wherein the flavor-enhancing additive is selected from the group consisting of fatty acid, monoglyceride and diglyceride.
 25. A frying medium comprising poly(dimethylsiloxane) and from about 0.0001 to about 1.0% v/v of a defoaming and flavoring additive selected from the group consisting of oleic acid, linoleic acid and food grade emulsifying agent containing an oleic or linoleic radical, wherein said medium is free form naturally-occurring animal and vegetable fats and oils.
 26. A medium according to claim 25 wherein the viscosity of the poly(dimethylsiloxane) is about 35 cSt.
 27. A medium according to claim 25 wherein the emulsifying agent is a monoglyceride or a diglyceride. 